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Four types of glaucoma occur in dogs. In open-angle glaucoma, pressure builds and damage occurs slowly. The American Cocker Spaniel, Basset Hound, Beagle, Boston Terrier, Miniature Poodle, Miniature Schnauzer and Norwegian Elkhound are prone to this type. Narrow-angle (also called closed-angle) glaucoma is more common. It is an emergency in which glaucoma comes on quickly and painfully and causes serious damage within as little as a few hours. Dogs prone to this type are the Alaskan Malamute, American Cocker Spaniel, Basset Hound, Chow Chow, Dalmatian, English Cocker Spaniel, Fox Terrier, Great Dane, Poodle (all sizes), Samoyed, Siberian Husky and Welsh Springer Spaniel. The third type is goniodysgenesis, in which a ligament in the eye is defective and may cause partial blockage of drainage. The American Cocker Spaniel, Basset Hound, Bouvier des Flandres, Chihuahua, Chow Chow, English Cocker Spaniel, Norwegian Elkhound, Poodle (Toy and Miniature), Samoyed, Siberian Husky and Terrier (some breeds) are among the breeds prone to this type. In pigmentary glaucoma, an excess of pigment cells block drainage. Cairn Terriers are prone to this type.

Glaucoma treatments include surgery, pills, eye drops or (rarely) removal of the eyeball. “Glaucoma is still one of the more difficult things to handle,” says Dr. Vainisi. “Even though there are literally dozens of glaucoma procedures, there still is not that ideal one … even in humans.”

Retinal Disorders. “Progressive retinal atrophy” (PRA) is the name for a group of conditions in which rods and cones die off; there is no treatment. Dogs who get PRA do so because they’ve inherited a defective gene. Although PRA strikes more than 100 breeds of dogs, different genes are responsible. Therefore, breeds differ in the age at which the condition appears, how fast the condition progresses, and the ratio of males to females among affected dogs. PRA appears during puppyhood in the Cardigan Welsh Corgi, Cairn Terrier, Collie, Gordon Setter, Great Dane, Irish Setter, Miniature Schnauzer and Norwegian Elkhound. In contrast, some breeds usually don’t develop PRA until adulthood. These include the American Cocker Spaniel, English Cocker Spaniel, Labrador Retriever, Lhaso Apso, Miniature Poodle, Portuguese Water Dog, Tibetan Spaniel and Tibetan Terrier. PRA occurs mostly in males in the Siberian Husky and Samoyed. Genetic tests for PRA are available for several breeds.

Other retinal problems include detachment of the retina from the back of the eye, inflammation and abnormal development. Causes include infection and injury. Some retinal disorders have no treatment, while others can be helped by surgery or treatment of the cause.

Dr. Vainisi, a pioneer of veterinary retinal surgery, treated movie star Benji for a detached retina in 2004. Another small dog, a Shih Tzu with two detached retinas, was his first case in 1985. “This was the love of her [the owner’s] life, this little dog,” Dr. Vainisi says. He asked the owner to bring the dog to Grand Rounds at the medical school at the University of Illinois at Chicago, where he was a faculty member. None of the ophthalmologists were willing to tackle the case because the retinas were completely detached and the procedure would be very difficult. But afterward, one of the ophthalmology residents volunteered to help. He came to Dr. Vainisi’s clinic the next evening with equipment for human retina surgery borrowed from the university, and they operated. “Within a matter of a couple of days, the dog got his vision back. It was really like a miracle,” Dr. Vainisi says.

It’s no coincidence that both these cases involved small dogs. According to Dr. Vainisi, several small breeds of dogs, including Boston Terriers, Jack Russell Terriers and Shih Tzus, love to pick up toys and shake them hard. “Fluid goes violently back and forth in the back of the eye, and it just rips the retina right off,” he says. “One moment they’re seeing, and the next moment they can be totally blind.”